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 A005846 Primes of the form n^2 + n + 41. (Formerly M5273) 108
 41, 43, 47, 53, 61, 71, 83, 97, 113, 131, 151, 173, 197, 223, 251, 281, 313, 347, 383, 421, 461, 503, 547, 593, 641, 691, 743, 797, 853, 911, 971, 1033, 1097, 1163, 1231, 1301, 1373, 1447, 1523, 1601, 1847, 1933, 2111, 2203, 2297, 2393, 2591, 2693, 2797 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Note that 41 is the largest of Euler's Lucky numbers (A014556). - Lekraj Beedassy, Apr 22 2004 a(n) = A117530(13, n) for n <= 13: a(1) = A117530(13, 1) = A014556(6) = 41, A117531(13) = 13. - Reinhard Zumkeller, Mar 26 2006 The link to E. Wegrzynowski contains the following incorrect statement: "It is possible to find a polynomial of the form n^2 + n + B that gives prime numbers for n = 0, ..., A, A being any number." It is known that the maximum is A = 39 for B = 41. - Luis Rodriguez (luiroto(AT)yahoo.com), Jun 22 2008 Contrary to the last comment, Mollin's Theorem 2.1 shows that any A is possible if the Prime k-tuples Conjecture is assumed. - T. D. Noe, Aug 31 2009 a(n) can be generated by a recurrence based on the gcd in the type of Eric Rowland and Aldrich Stevens. See the recurrence in PARI under PROG. - Mike Winkler, Oct 02 2013 These primes are not prime in O_(Q(sqrt(-163)). Given p = n^2 + n + 41, we have ((2n + 1)/2 - sqrt(-163)/2)((2n + 1)/2 + sqrt(-163)/2) = p, e.g., 1601 = 39^2 + 39 + 41 = (79/2 - sqrt(-163)/2)(79/2 + sqrt(-163)/2). - Alonso del Arte, Nov 03 2017 From Peter Bala, Apr 15 2018: (Start) The polynomial P(n) := n^2 + n + 41 takes distinct prime values for the 40 consecutive integers n = 0 to 39. It follows that the polynomial P(n-40) takes prime values for the 80 consecutive integers n = 0 to 79, consisting of the 40 primes above each taken twice. We note two consequences of this fact. 1) The polynomial P(2*n-40) = 4*n^2 - 158*n + 1601 also takes prime values for the 40 consecutive integers n = 0 to 39. 2) The polynomial P(3*n-40) = 9*n^2 - 237*n + 1601 takes prime values for the 27 consecutive integers n = 0 to 26 ( = floor(79/3)). In addition, calculation shows that P(3*n-40) also takes prime values for n from -13 to -1. Equivalently put, the polynomial P(3*n-79) = 9*n^2 - 471*n + 6203 takes prime values for the 40 consecutive integers n = 0 to 39. This result is due to Higgins. Cf. A007635 and A048059. (End) REFERENCES O. Higgins, Another long string of primes, J. Rec. Math., 14 (1981/2) 185. Paulo Ribenboim, The Book of Prime Number Records. Springer-Verlag, NY, 2nd ed., 1989, p. 137. N. J. A. Sloane and Simon Plouffe, The Encyclopedia of Integer Sequences, Academic Press, 1995 (includes this sequence). LINKS Zak Seidov, Table of n, a(n) for n = 1..10000. Phil Carmody, Drag Racing Prime Numbers! - Vladimir Joseph Stephan Orlovsky, Jul 24 2011 Richard K. Guy, The strong law of small numbers. Amer. Math. Monthly 95 (1988), no. 8, 697-712. [Annotated scanned copy] R. A. Mollin, Prime-producing quadratics, Amer. Math. Monthly 104 (1997), 529-544. Eric Weisstein's World of Mathematics, Euler Prime Eric Weisstein's World of Mathematics, Prime-Generating Polynomial FORMULA a(n) = A056561(n)^2 + A056561(n) + 41. EXAMPLE a(39) = 1601 = 39^2 + 39 + 41 is in the sequence because it is prime. 1681 = 40^2 + 40 + 41 is not in the sequence because 1681 = 41*41. MAPLE for y from 0 to 10 do U := y^2+y+41; if isprime(U) = true then print(U) end if ; end do: # Matt C. Anderson, Jan 04 2013 MATHEMATICA Select[Table[n^2 + n + 41, {n, 0, 59}], PrimeQ] (* Alonso del Arte, Dec 08 2011 *) PROG (PARI) for(n=1, 1e3, if(isprime(k=n^2+n+41), print1(k", "))) \\ Charles R Greathouse IV, Jul 25 2011 (Haskell) a005846 n = a005846_list !! (n-1) a005846_list = filter ((== 1) . a010051) a202018_list -- Reinhard Zumkeller, Dec 09 2011 (PARI) {k=2; n=1; for(x=1, 100000, f=x^2+x+41; g=x^2+3*x+43; a=gcd(f, g-k); if(a>1, k=k+2); if(a==x+2-k/2, print(n" "a); n++))} \\ Mike Winkler, Oct 02 2013 (GAP) Filtered(List([0..100], n->n^2+n+41), IsPrime); # Muniru A Asiru, Apr 22 2018 (MAGMA) [a: n in [0..55] | IsPrime(a) where a is n^2+n+ 41]; // Vincenzo Librandi, Apr 24 2018 CROSSREFS Cf. A048988, A007634, A056561, A002378, A007635. Intersection of A000040 and A202018; A010051. Cf. A048059. Sequence in context: A296921 A155884 A202018 * A273756 A154498 A223458 Adjacent sequences:  A005843 A005844 A005845 * A005847 A005848 A005849 KEYWORD nonn,easy AUTHOR EXTENSIONS More terms from Henry Bottomley, Jun 26 2000 STATUS approved

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Last modified October 23 14:54 EDT 2019. Contains 328345 sequences. (Running on oeis4.)